A funny thing happened when I was getting the bike ready for Bub's.
I was late, as usual, pulling it all together, because the new fabricated stainless steel fuel tank took longer than expected, then my first shot at the whole fuel system didn't work and I had to rethink the plan, then it took awhile to find a fuel return pump that would hold up to the nitro, etc. By the time I got it all sorted out, I only had a few days left to tune it up before we had to pack up and head to the salt. Keep in mind I had never played with methanol or nitro before at all. I had read everything I could get my hands on, and talked to lots of people, but that's all.
So I finally get the thing on the dyno. I set it up on on straight methanol, using the smallest jet that came with my nitro carb which is still a little too big for straight methanol by my calculations, I tune the thing up, and it's making real good power, better than it ever did on gasoline. All is well. Time to put some nitro to it and see what it'll do.
I make the appropriate jetting and timing changes, mix up some nitro at a safe but significant percentage that should give a 40% or so boost in power, do a nitro pull, and the computer crashes. Damn.
3 hours later, after getting another computer and installing all the software, I'm ready to try again. Everything works, but the damn thing just doesn't make much power. I fiddle with it, get my arms around the jetting and timing, but I'm getting maybe 10% more power than I did with straight methanol. WTF?
The next few days is a mad scramble of trying stuff. I overnighted in a fancy and expensive ignition system. Same thing. I talk with everyone I know, nobody has any ideas. Finally I go back to straight methanol. It's way down on power from where it was when I started. Ah-ha! I run leak down tests, no problem. I pull heads and look around and make measurement. No problems. I check for wet sumping. Everything's perfect. The damn thing just won't make power and I have no idea why.
Finally I get to the last night before I have to leave for the salt. I'm stumped. I finally just say the hell with it, let's put more nitro to it and see what it does. I put as much to it as I think I can get away with given the compression ratio and the jets I have. I do one pull, it makes decent power, still 10% or so BELOW what it used to make on nitrous. I decide to take it to the salt anyway and see what it does and see if I can't learn something.
Well, the bike is fast, noticeably faster than it ever was on nitrous. Once we get the gearing right, with a little tailwind we run 217.9, 10mph faster than we've ever run. We bag a record at 213. Then we try to put just a little more nitro to it and we hurt a piston. We had the thing right on the edge already. Overall a very succcessful event for us, and we definitely learned a lot about the nitro.
I know that there's no freakin' way the bike should've gone that fast on that much power. I rationalize it by telling myself it's a load sensitive fuel and the dyno's not loading it enough to make it work. But in the back of my mind, I don't buy it.
About a month later, I'm tuning a customer's bike, and the SOB just won't make power. It's a combination I'm familiar with, and I knew how much power it should make, but this thing is just WAY down. I run all the checks, everything is fine.
Suddenly a light bulb came on. When the computer had crashed and I replaced it, I reloaded the dyno software. One of the things the installation software asks you is the dyno model. My dyno is a dual-roller kart/atv dyno with a motorcycle kit. What if I had told it I had a motorcycle dyno? Te dyno works by just timing the spin up of the drum. The motorcycle dyno has a smaller, single roller drum. If the software thinks I have a motorcycle dyno, all the readings will come out low!
I reloaded the software, and like magic, the customer's bike was making the power it should.
In the end, it worked out well. If not for the mistake loading the dyno software, I would've come out to the event too conservative on the nitro. The mistake forced me to push it right to the edge, farther than I intended, and I learned that much more as a result.
Now to just get it to the next level. But safety has to come first. This stuff is downright dangerous at higher percentages.
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